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Evaluating breast-conserving surgery for low-risk ductal carcinoma in situ

Prospective Evaluation of Breast-Conserving Surgery Alone in Low-Risk Ductal Carcinoma in Situ Defined by a Molecular Expression Assay Combined With Clinico-Pathological Features

Observational Ontario Clinical Oncology Group (OCOG) · NCT04797299

This study is testing if certain factors can help identify women with low-risk ductal carcinoma in situ who might not need radiation therapy after breast-conserving surgery.

Quick facts

Study typeObservational
Enrollment526 (estimated)
Ages46 Years and up
SexFemale
SponsorOntario Clinical Oncology Group (OCOG) Academic / other
Drugs / interventionsradiation
Locations24 sites (Calgary, Alberta and 23 other locations)
Trial IDNCT04797299 on ClinicalTrials.gov

What this trial studies

This observational study aims to assess whether clinicopathological factors combined with the Oncotype DX DCIS score can help identify women with low-risk ductal carcinoma in situ (DCIS) who may not need radiation therapy after breast-conserving surgery. The study will involve screening 809 women, with the goal of enrolling approximately 526 participants who have a predicted 10-year risk of local recurrence of 10% or less. Participants will have their tumor specimens analyzed to determine their DCIS score, and they will be followed for up to 10 years to monitor outcomes. Data on patient demographics, surgery details, and tumor characteristics will be collected throughout the study.

Who should consider this trial

Good fit: Ideal candidates are women over 45 years old with low-risk DCIS who have undergone breast-conserving surgery with clear margins.

Not a fit: Patients with multifocal DCIS or a history of invasive breast cancer will not benefit from this study.

Why it matters

Potential benefit: If successful, this study could help reduce unnecessary radiation therapy for women with low-risk DCIS, improving their quality of life.

How similar studies have performed: Other studies have explored similar approaches, but this specific evaluation of the Oncotype DX DCIS score in this context is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. Female patient \> 45 years of age with DCIS without microinvasion.
2. Tumour size ≤ 2.5cm.
3. Treated by BCS with clear resection margins ≥ 2 mm or no residual disease on re-excision.\*

   \* Patients with anterior margins and posterior margins ≥1 mm are eligible. Or if the dissection was confirmed to be taken to skin and down to fascia with no DCIS present at inked margins.
4. Oncotype DX DCIS score with a predicted 10-year risk of LR ≤10%.

Exclusion Criteria:

1. Multifocal DCIS.
2. History of any invasive breast cancer or non-invasive breast cancer in the ipsilateral breast.
3. Synchronous or previous invasive or non-invasive breast cancer.
4. Prior history of invasive cancer within the last 5 years, excluding non-melanoma skin cancers.
5. ECOG performance status ≥3.
6. Life expectancy \<10 years.
7. Geographic inaccessibility for follow-up.

Where this trial is running

Calgary, Alberta and 23 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions DCISDuctal Carcinoma in SituBreast Conserving SurgeryOncotype DX DS
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.